Title :
Selective dry etching of GaN over AlGaN in BCl3/SF6 mixtures
Author :
Buttari, D. ; Chini, A. ; Chakraborty, A. ; McCarthy, L. ; Xing, H. ; Palacios, T. ; Shen, L. ; Keller, S. ; Mishra, U.K.
Author_Institution :
Dept. of Electr. & Comput. Eng., California Univ., Santa Barbara, CA, USA
Abstract :
Inductively coupled plasma (ICP) etching of GaN with high selectivity over Al0.22Ga0.78N in BCl3/SF6 mixtures has been studied. Selectivity and surface morphology were investigated over a wide range of pressures (3.75-37.5mTorr), RF powers (30-120 W), ICP powers (100-400 W), and SF6/BCl3 ratios (0.1-0.7). Higher pressures, lower dc biases, and higher SF6/BCl3 ratios increased the GaN to AlGaN selectivity. Selectivities up to 25 were measured by laser interferometry. A root mean square (rms) surface roughness of 0.67 nm was measured by atomic force microscopy (AFM) after removal of 0.5 μm from a GaN template (process selectivity: 15, as-grown rms surface roughness: 0.56 nm). A degradation in surface morphology, with the gradual formation of pits, was observed for selectivities above 10.
Keywords :
III-V semiconductors; aluminium compounds; boron compounds; gallium compounds; plasma materials processing; sputter etching; sulphur compounds; surface morphology; surface roughness; wide band gap semiconductors; 100 to 400 W; 3.75 to 37.5 mTorr; 30 to 120 W; AlGaN; BCl3-SF6; BCl3/SF6 mixtures; atomic force microscopy; inductively coupled plasma etching; laser interferometry; selective dry etching; surface morphology; surface roughness; Aluminum gallium nitride; Atomic force microscopy; Atomic measurements; Dry etching; Force measurement; Gallium nitride; Plasma applications; Rough surfaces; Surface morphology; Surface roughness;
Conference_Titel :
High Performance Devices, 2004. Proceedings. IEEE Lester Eastman Conference on
Print_ISBN :
981-256-196-X
DOI :
10.1109/LECHPD.2004.1549684
